Moderate supplementation with natural alpha-tocopherol decreases platelet aggregation and low-density lipoprotein oxidation

Previous studies have shown that oral administration of 300 mg alpha-tocoph erol/day to healthy volunteers decreases platelet function and enhances the ir sensitivity to the platelet inhibitor, prostaglandin E-1,, when full dos e-response curves to a range of agonist concentrations are made. In this st udy, the effects of oral doses of natural alpha-tocopherol (75, 200 and 400 IU/day) were studied in order to determine whether the same effects might be achieved with lower intakes of vitamin E and whether inhibition is relat ed to the platelet levels of the antioxidant in platelet membranes. Twenty two subjects undertook the supplementation regime, divided into three units of 2 weeks, each cycling through each of the dosages. The results show tha t uptake of vitamin E by the platelets was optimal at 75 IU/day, correlatin g with the maximal influence on platelet aggregation and platelet responsiv eness to inhibition by PGE1, increased supplemental levels exerting no grea ter effects. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.